CC1021-RTR1 datasheet(59/92 Pages) TI

59 / 92 page

CC1021

SWRS045

Page 59 of 91

Item

CL= 12 pF

CL= 16 pF

CL= 22 pF

6.8 pF

15 pF

27 pF

6.8 pF

15 pF

27 pF

Table 28. Crystal oscillator component values

20.

Built-in Test Pattern Generator

The CC1021 has a built-in test pattern

generator that generates a PN9 pseudo

random sequence. The PN9_ENABLE bit

in the MODEM register enables the PN9

generator. A transition on the DIO pin is

required after enabling the PN9 pseudo

random sequence.

The PN9 pseudo random sequence is

defined by the polynomial x9 + x5 + 1.

The PN9 sequence is ëXORíed with the

DIO signal in both TX and RX mode as

shown in Figure 34. Hence, by transmitting

only zeros (DIO = 0), the BER (Bit Error

Rate) can be tested by counting the

number of received ones. Note that the 9

first received bits should be discarded in

this case. Also note that one bit error will

generate 3 received ones.

Transmitting only ones (DIO = 1), the BER

can be tested by counting the number of

received zeroes.

The PN9 generator can also be used for

transmission of ëreal-lifeí data when

measuring narrowband ACP (Adjacent

Channel Power), modulation bandwidth or

occupied bandwidth.

XOR

Tx out (modulating signal)

Tx data (DIO pin)

XOR

Rx pseudo random sequence

Rx in (Demodulated Rx data)

Rx out (DIO pin)

Tx pseudo random sequence

Figure 34. PN9 pseudo random sequence generator in TX and RX mode

CC1021-RTR1 Datasheet(PDF) 59 Page - Texas Instruments

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